Multi-pole vacuum switch with an insulation assembly surrounding each vacuum interrupter

ABSTRACT

A multi-pole vacuum switch has an insulation assembly for each pole, which is composed of shell-like insulating elements. In addition to a space provided for receiving the vacuum interrupter, chambers are formed by wall sections, which are provided for receiving mechanical and electrical components of a pole unit. In particular, these electrical components are a loop-shaped, flexible strip conductor, a lever arrangement, contact springs and current transformers. Tensioning bolts which penetrate all the pole units connect the pole units to a pole block. The invention is suitable for use in vacuum power switches, in particular for low operating voltages.

BACKGROUND OF THE INVENTION

The present invention relates to a multi-pole vacuum switch having onevacuum interrupter per pole. Each vacuum interrupter has an essentiallycylindrical housing and cylindrically shaped end flanges which terminatethe housing axially and a connection bolt which extends through one ofthe end flanges and is displaceably mounted for switching the vacuumswitch on and off. Each of the vacuum interrupters is surrounded by aninsulation assembly. The insulation assemblies for all the poles arearranged one next to the other and include a connection chamber arrangedin the axial extension of the associated vacuum interrupter. Thedisplaceable connection bolt of the vacuum interrupter projects into theconnection chamber. The connection chamber includes a loop-shaped,flexible strip conductor for connecting the displaceable connection boltto an external connection element. A drive device, which is common toall poles, switches the vacuum interrupters on and off for all thepoles. A drive lever is provided for each of the vacuum interrupters,which is pivotably mounted in the associated insulation assembly.

A vacuum switch of this kind is shown in, for example, German Patent No.DE-B-23 22 372. The insulation assemblies for the shown vacuum switchare of essentially cylindrical design and are divided transversely withrespect to the longitudinal axis. The head part of each insulationassembly contains a bearing point for a two-armed lever for driving theassociated vacuum interrupter. A lever part, which projects out of thehead part is connected to a drive rod of the drive device. A pluralityof such pole units are attached to a drive housing in accordance withthe desired number of poles.

In view of German Patent No. DE-B- 23 22 372, an object of the presentinvention is based on simplifying the installation of the vacuuminterrupters in the insulation assembly while maintaining the principleof protecting the vacuum interrupters on all sides. At the same time, itis an object of the present invention to provide conditions for largelyintegrating assemblies relating to the vacuum switch poles, such asconnection devices, contact springs, drive components for theinterrupters, or similar assemblies.

SUMMARY OF THE INVENTION

These and other objects are achieved by the vacuum switch of the presentinvention. The vacuum switch of the present invention is of the typedescribed above having the following further features. Each insulationassembly comprises two shell-like insulating elements which receive theassociated vacuum interrupter between them. Each insulation assembly hasat least one approximately semicylindrical recess matched to one of theend flanges of the vacuum interrupter. A strip conductor is arranged inthe connection chamber having legs which extend transversely withrespect to the longitudinal axis of the vacuum interrupter in such a waythat forces resulting from a current flowing through the strip conductorcan be used to compensate contact-breaking forces within the vacuuminterrupter. The insulating elements are each provided with at least twothrough-openings for receiving tensioning bolts which penetrate all ofthe insulating elements. A pole block is provided which is formed fromthe insulation assemblies and is arranged between side walls, which aredesigned to protrude beyond the pole block for attaching to the drivedevice.

Because of the longitudinal division of the insulation assembly, theentire current path of a pole can be installed in one of the shell-likeinsulating elements before the other shell-like insulating element isfitted on and an enclosed pole unit is formed. A plurality of such poleunits can be joined one to the other and are then connected bytensioning bolts to form a pole block. Because of this design, thevacuum switch is divided up essentially into two large assemblies, i.e.,the pole block with the protruding side walls and the drive device whichis to be attached between the side walls. During the assembly of thepole block with the drive device, it is only necessary to make onemechanical connection to the drive kinematics which are pole-related andcontained in each pole unit.

Furthermore, in contrast to the arrangement provided in the case of thevacuum switch according to the German Patent No. DE-B-23 22 372mentioned above, where legs of the flexible conductor are arranged torun parallel to the longitudinal axis of the vacuum interrupter, it isachieved that the disengaging forces between the contact members of thevacuum interrupter, which are produced by a short-circuit current, areable to be compensated by means of the loop forces.

It is advantageous if the insulating elements are dimensioned toprotrude beyond the associated vacuum interrupter (if the protrudingareas are bounded at least partially by wall sections to form chambers),and if the shape of the chambers is matched to electrical and/ormechanical components which are provided for operating the vacuuminterrupter.

Such an additional chamber can be, for example, a measurement chamberwhich is arranged adjacent to the connection chamber and can receive acurrent transformer. This arrangement is particularly expedient inconjunction with a connection element which is an extension of thelongitudinal axis of the vacuum interrupter or extends parallel thereto.It provides the possibility of plugging a current transformer on to theconnection element when required, and replacing it easily.

The measurement chamber which is provided for receiving a currenttransformer can be closed off from the outside by an insulating closureelement which is to be connected to the shell-like insulating elementsand has a feedthrough opening for the associated connection element. Theclosure element not only supports the connection element but alsosecures the current transformer. The supporting function for theconnection element is also realized if no current transformer is usedand only the empty measurement chamber is bridged by the closureelement.

The insulation assemblies can be provided with additional chambers. Inparticular, to the side of the space which is intended for receiving theassociated vacuum interrupter, the insulation assembly can receive aspring chamber for receiving at least one spring which provides thecontact force of the vacuum interrupter. On the opposite side, theinsulation assembly can receive a drive chamber for receiving a leverarrangement which transmits the drive movement of the drive device tothe vacuum interrupter. The lever arrangement here can be designed insuch a way that a convenient connection or coupling to the drive deviceis produced. In addition, the insulation assemblies can have, in eachcase underneath the spring chamber, a wall section with an undercut forthe engagement of a bolt which serves as a fixed counterbearing of acontact spring.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagrammatic plan view of a multi-pole vacuum switch.

FIG. 2 shows a pole unfit of the multi-pole vacuum switch according toFIG. 1 in the opened state.

FIG. 3 illustrates the pole unit according to FIG. 2 in the closed statewith a view of the narrow sides.

FIG. 4 shows one of the shell-like insulating elements from which theinsulation assembly of the pole unit according to FIGS. 2 and 3 iscomposed.

FIG. 5 shows the insulating element according to FIG. 4 from above.

DETAILED DESCRIPTION

The vacuum switch 1 shown in FIG. 1 has a three pole design and hasthree pole units 2 which are arranged one next to the other withoutspacing. The pole block 3, which is formed in this way, is held togetherby tensioning bolts 4 which penetrate the pole units 2 and also, at thesame time, grip side walls 5 which form the lateral termination of thepole block 3 and which are designed to protrude beyond the pole block 3.Between the protruding sections of the side walls 5 there is a drivedevice 6 which serves in a known manner to switch on and off the vacuuminterrupters contained in the pole units 2.

The components of one of the pole units 2 are explained in greaterdetail below with reference to FIGS. 2 to 5, and the basic design isdescribed with reference to FIGS. 2 and 3.

The pole unit 2 has a vacuum interrupter 10 which has a housing 11 withan upper end flange 12 and a lower end flange 13. The lower end flange13 is also one connection point of the vacuum interrupter 10. Aconnection bar 14 bent at a right angle is provided as a connectiondevice. A displaceably mounted connection bolt 15, to which the one leg16 of a flexible strip conductor 17 is attached, extends through theupper terminating flange 12. The strip conductor 17 has an approximatelyloop-shaped design and has a shorter leg 18 which is located oppositeand approximately parallel to the leg 16 and is coupled to a straightconnection bar 20. The connection bar 20 extends upwards, parallel tothe extension of the longitudinal axis of the vacuum interrupter 10,while the legs of the strip conductor 17 are arranged runningtransversely with respect to this longitudinal axis.

The components described above form the current path of the pole unit 2.This current path is contained in an insulation assembly 23 formed fromtwo approximately shell-shaped insulating elements 21 and 22. First, theshape of the insulating element 22 will be explained in greater detailwith reference to FIGS. 4 and 5.

As can be seen from FIGS. 4 and 5, the first insulating element 22 haswall sections which project out of an essentially planar wall component24, and a number of spaces or chambers are formed therein. Two wallsections 25 and 26 are provided here with approximately semicircularrecesses 27 and 28 which are matched to the shape of the end flanges 12and 13 of the vacuum interrupter 10. A space for receiving the vacuuminterrupter 10 is formed by the wall sections 25 and 26, in conjunctionwith corresponding wall sections of the associated mirror-invertedinsulating element 21. If both semicircular recesses are dimensioned tomatch the end flanges 12 and 13, the vacuum interrupter 10 is clampedtight at both ends. In contrast, if it is desired to secure only one end(for example the end flange 12) of the vacuum interrupter 10, the recess28 can be of a widened design 28A, as is shown by broken lines in FIG.4.

A further wall section 30, which is arranged approximately parallel tothe wall section 25, bounds a connection chamber 31 which is providedfor receiving the flexible strip conductor 17 shown in FIG. 2. Towardsits bottom, the connection chamber 31 is connected to a drive chamber 29which is located to the side of the vacuum interrupter 10. Upper wallcomponents 32 and 33 extend approximately parallel to the longitudinalaxis of the vacuum switching chamber 10 (FIG. 2) and each of the upperwall components contain a recess 34 for inserting a nut. FIGS. 2 and 3show that a measurement chamber 37 is formed by fitting on a closureelement 35 which extends beyond the entire width of the insulationassembly 23 and is connected to the insulating elements 21 and 22 via atotal of four attachment screws 36. A current transformer 38, whosecontours are shown by a broken line, can be accommodated in themeasurement chamber 37. The wall section 30 and the closure element 35have flush openings for the aforementioned upper connection bar 20 topass through.

In addition, FIG. 4 shows, on the right-hand side of the space which isprovided for receiving the vacuum interrupter, an angular wall section40 on whose underside an undercut 41 is located. As a result, a springchamber 42 is formed which serves, in accordance with FIGS. 2 and 3, toreceive two contact springs 43. The contact springs 43 are shown in theuntensioned state, which results after the installation of the currentpath and the connection of the movable connection bolt 15 to parts whichwill be explained later. The pretensioning of the contact springs 43,which is required for operation, is brought about by inserting a bolt44, indicated by dot-dashed lines, into lower eyelets 45 of the twocontact springs 43 and by hooking this bolt into the undercuts 41 ofboth of the associated insulating elements 21 and 22. In addition, it isassumed in FIGS. 2 and 3 that the drive parts are free of forces andtherefore the vacuum interrupter 10 is under the influence ofatmospheric air pressure in the switched-on state.

The drive device 6, which is shown diagrammatically in FIG. 1,interacts, according to FIG. 2, with one coupling lever 46 of each ofthe pole units 2. The coupling lever 46 is pivotably mounted on a bolt47 (FIG. 2) which engages at both ends in bearing eyes 48 of theinsulating elements 21 and 22. One of the bearing eyes 48 is shown inFIG. 4. An adjustable coupling rod 50, which extends approximatelyparallel to the longitudinal axis of the vacuum interrupter 10, islocated in the drive chamber 29 and connects the coupling lever 46 to adrive lever 51 located in the connection chamber 31. The drive lever 51is formed of an approximately U-shaped sheet-metal part and has legs 52and a central part 53 which does not need to extend beyond the entirelength of the legs 52. The drive lever 51 is mounted by a bearing bolt54 on the displaceable connection bolt 15 using a mounting element 54A.A further articulation bolt 55 extends through the legs 52 and engageswith its ends in each case one window-like recess 56 which is shown bybroken lines and whose lower edge forms a stop face 57 for thearticulation bolt 55. An end part 58, which protrudes beyond thearticulation bolt 54, of the drive lever 51 serves as counterbearing forthe aforesaid contact springs 43, specifically either directly or by theillustrated clips 59 in conjunction with a bolt 60 which connects theclips 59.

The flexible strip conductor 17 is located essentially between the legs52 of the drive lever 51 and is in this way accommodated in a veryspace-saving manner. The desired function is achieved in that the lowerleg 16 of the strip conductor 17 can be supported against the centralpart 53 while the upper leg 18 rests against the wall section 30. Aforce which spreads apart the legs 16 and 18 of the strip conductor 17and is dependent on the respective current flowing presses the drivelever 51 downwards in such a way that the contact force of the vacuuminterrupter 10 is increased.

In the switched-on state, the articulation bolt 55 is at a specificdistance from the stop face 57 so that the bearing bolt 54 forms thepivot bearing of the drive lever 51. If the drive device 6 (FIG. 1) isreleased for switching the vacuum interrupter off, which corresponds tothe coupling lever 46 being released, the right-hand end, connected tothe coupling rod 50, of the drive lever 51 is no longer secured. Thedrive lever 51 then pivots about its bearing bolt 54 in a counterclockwise direction until the articulation bolt 55 comes to rest againstthe stop face 57 and the stop face 57 now forms the pivot bearing of thedrive lever 51. The contact springs 43 now act in an opening fashionwith the lever arm of the end part 58 of the drive lever 51. The use ofsprings in such a way that they act both as contact springs and asswitch-off springs is known per se in vacuum switches and can be found,for example, in German Patent No. DE-A-34 14 016.

For receiving the tensioning bolts 4 shown in FIG. 1, the insulatingelements 21 and 22 are provided with flush through-openings 61. Theinsulating elements 21 and 22 are held together by connecting screws 62before being ultimately connected by the tensioning bolts 4. Theconnecting screws 62 penetrate the wall sections of the insulatingelements 21 and 22 and engage in the connection bars 14 and 20.

As is clear from the description above, the use of the insulatingelements permits a very space-saving arrangement of the vacuuminterrupters including their associated assemblies. At the same time,the loop-shaped strip conductor is integrated into the drive partsvirtually without additional space being required. Therefore, theinvention is particularly suitable for the construction of compactswitching devices, e.g. for circuit breakers in the voltage range of upto 1000 V.

We claim:
 1. A multi-pole vacuum switch comprising:a vacuum interrupterfor each pole of the multi-pole vacuum switch, where each vacuuminterrupter comprises:an essentially cylindrical housing havingcylindrically shaped upper and lower end flanges; and a connection boltextending through said upper end flange, said connection bolt beingdisplaceably mounted for switching said vacuum interrupter on and off; adrive device coupled to each pole of said multi-pole vacuum switch, saiddrive device capable of switching each of said vacuum interrupters onand off; and an insulation assembly surrounding each of said vacuuminterrupters, such that the insulation assemblies for all of said vacuuminterrupters are arranged one next to another, where each saidinsulation assembly comprises:a connection chamber arranged in aposition which is axially displaced with respect to the vacuuminterrupter, where said connection bolt of said vacuum interrupterprojects into said connection chamber, said connection chamber includesa loop-shaped flexible strip conductor capable of coupling saidconnection bolt to an external connection element; a drive lever coupledto the drive device of said vacuum interrupter, said drive lever beingpivotably mounted in said insulation assembly; first and secondshell-like insulating elements, each having at least one semicylindricalrecess capable of receiving one of said lower and upper end flanges,such that said first and second shell-like insulating elements receivesaid vacuum interrupter between them; said strip conductor of saidvacuum interrupter being arranged in said connection chamber, where saidstrip conductor includes first and second legs extending transverselywith respect to a longitudinal axis of the vacuum interrupter, such thatforces resulting from a current flowing through said strip conductor arecapable of compensating contact-breaking forces within said vacuuminterrupter; and each of said insulating elements includes at least twothrough-openings capable of receiving tensioning bolts which penetrateall of said insulating elements in said multi-pole vacuum switch, suchthat a pole block is formed of said insulating assemblies arrangedbetween at least two side walls, said side walls protruding beyond saidpole block for attachment to said drive device.
 2. The multi-pole vacuumswitch of claim 1, wherein a portion of each of said first and secondinsulating elements protrude beyond the surrounded vacuum interrupter,such that said portions are bound at least partially by wall sections ofsaid first and second insulating elements to form at least oneadditional chamber, such that a shape of each additional chambercorresponds to electrical and mechanical components for operating saidvacuum interrupter.
 3. The multi-pole vacuum switch of claim 2, whereinone of said additional chambers is a measurement chamber which receivesa current transformer, said measurement chamber being arranged adjacentto said connection chamber, where said measurement chamber is penetratedby said connection element, said connection element is an extension ofthe longitudinal axis of said vacuum interrupter and is coupled to thefirst leg of said flexible strip conductor.
 4. The multi-pole vacuumswitch of claim 3, wherein said measurement chamber is terminated by aninsulating closure element which is releasably attached to both of saidfirst and second insulating elements of said insulation assembly, wheresaid insulating closure element has a feedthrough opening for saidconnection element.
 5. The multi-pole vacuum switch of claim 1, whereineach insulation assembly includes a spring chamber adjacent to a spacefor receiving said vacuum interrupter, said spring chamber receiving atleast one contact spring providing a contact force to the vacuuminterrupter, and a drive chamber adjacent to said space for receivingsaid vacuum interrupter and opposite to said spring chamber, said drivechamber receiving a lever arrangement coupled to the drive device and tosaid contact spring for transmitting drive movement and contact force tothe vacuum interrupter.
 6. The multi-pole vacuum switch of claim 5,wherein said insulation assembly includes an undercut for engaging anadditional bolt, said additional bolt acting as a fixed counterbearingof said contact spring and is arranged on a wall section which boundssaid spring chamber.